trs group taking off with thermal conduction heating
TRANSCRIPT
TRS TCH 20210319 acfTRS Whitepaper on TCH March 2021 Page 1
TRS Group Taking Off with Thermal Conduction Heating
Gorm Heron, Andrew Small, Dan Oberle and Emily Crownover TRS Group, Inc.
Started in 2000, TRS Group (TRS) has been the premier provider of electrical resistance heating. To better serve our customers, TRS now provides three heating technologies:
• OptiFluxÒ Electrical Resistance Heating (ERH) – using electrodes, TRS passes electricity through the subsurface, achieving temperatures up to the boiling point of water.
• FlexHeaterÒ Thermal Conduction Heating (TCH) – TRS heats steel borings, transferring heat to the formation by conduction, reaching temperatures as high as 400oC among the borings.
• EcoSteamTM Steam Enhanced Extraction (SEE) – using injection and multiphase extraction wells, TRS injects steam into the formation and treats the collected fluids. Heating is limited to the temperature of steam.
Our research and development team has developed a patented TCH technology (Oberle et al. 2018) with targeted power delivery, reducing operating time and lowering costs.
TCH – what do you really need down-hole?
The steel casing reaches temperatures in the range of 300 to 800oC. When using electricity, it is important that the heater does not short to the casing. Therefore, the heater needs to be coated with a non-conductive material (silica, glass, ceramic) or centralized such that the metal part of the heater cannot touch the inside of the casing. As the heater wire is metal, TRS places ceramic spacers to prevent the wire from touching the casing, as shown in Figure 1. TRS offers multiple, patented and patent-pending FlexHeater® elements based on site conditions and goals. The TRS rod-style heater uses an alloy that is more flexible and sustainable than the systems others have used for decades. TRS uses this element in vertical, horizontal and angled boreholes, working around sensitive site infrastructure.
Heat movement is governed by matrix thermal diffusivity, which is the ratio of thermal conductivity to heat capacity. Thermal diffusivity varies with site stratigraphy and is based on water content, porosity and mineralogy. Even when these changes are modest (on the order of 1 to 3 times between a dry soil and wet clay), the ability of the formation to conduct heat away from the heater boring will vary.
The more uniform a site is heated, the less energy is used. A uniform heating profile requires different power inputs over depth. Therefore, it is desirable to control power delivery rates to different strata.
Some heaters accomplish this by varying the heater rod diameter, often with a boosted section at the top and bottom. TRS developed a heater with more flexibility in terms of power density over depth and time, allowing adjustment of the heat output as the collected data teaches us about the
Figure 1. FlexHeaterÒ element which provides flexibility to control power input
TRS Whitepaper on TCH March 2021 Page 2
formation. The TRS design allows us to remove, adjust and re-insert the heaters, enabling precise heating with less energy use.
Full-scale TCH remedy in North Carolina
TRS completed a FlexHeater® TCH full-scale project in North Carolina in 2019. The site had 32 heaters, each approximately 60 feet deep. Figure 2 shows a heater connection and the well field. Learning much about optimizing heater operations, TRS met the contractual goals and objectives.
Figure 2. FlexHeaterÒ TCH Operations in North Carolina in 2019
TCH Treatment in China
TRS China completed a large FlexHeater® TCH project in Nanjing, China. Operations with 420 heaters started in 2019. TRS China treated a 42,000 cubic meter source zone, concluding operations in 2020. The site was heavily contaminated with chlorophenols and other minimally volatile compounds. The value engineering designs for and lessons learned from this large, fast-paced project have been helpful for subsequent opportunities.
Figure 3. FlexHeaterÒ TCH Operations in Nanjing, China
TRS Whitepaper on TCH March 2021 Page 3
TCH at a Former Manufacturing Facility
TRS is implementing the FlexHeater® TCH technology under a large former manufacturing facility in Arkansas. TCH is well-suited to meet the challenging site conditions, which include limited access, dry vadose zone sediments, and interface to bedrock. TRS targeted three chlorinated volatile organic compounds (CVOCs) source zones with 154 vertical and angled heaters. TRS has removed over 4,000 pounds of CVOCs, achieved the remedial goals ahead of schedule in one of the areas and anticipates project completion by the Summer 2021.
Figure 3. An operating FlexHeaterÒ TCH site in Arkansas
Challenging TCH project under a large building in New Jersey
A commercial client approached TRS to apply TCH at a manufacturing facility in New Jersey. We are performing thermal treatment at depths of 50 to 120 feet below grade and installing more than four miles of heaters. Because much of the TCE source zone is located below the active facility, which must remain clean, TRS cannot drill from those rooms; instead, we are accessing the treatment zone from a separate room using angle drilling methods. To minimize costs, TRS designed, developed and tested a novel 200- foot long heater. We can install it at any angle and deliver depth-specific optimized power that allows for virtually no heating over the first 50 feet. The patent-pending design will keep the building cool, while heating the target zone to boiling temperatures. Installation started in 2020 and operations will start in 2021.
TCH treatment in Brazil
A TRS Doxor TCH project is in the design phase for implementation at a site in Sao Paulo, Brazil. The site is heavily contaminated by diesel range organics and has relatively stringent cleanup criteria for soil and groundwater. Using 113 FlexHeater® wells to deliver 500 kW or power to three source zones, TRS Doxor will complete the project in 2021.
Award of Two ESTCP Projects for PFAS Treatment using TCH
The remediation of per- and polyfluoroalkyl substances, also known as PFAS, is becoming increasingly important. The environmental industry is recognizing the challenges of developing analytical methods for
TRS Whitepaper on TCH March 2021 Page 4
PFAS in water, vapor and soil. At many U.S. Department of Defense (DOD) sites, stockpiles of untreated soil are growing, with no good or economical solution in sight. Source areas continue to leach PFAS to groundwater, impacting drinking water aquifers.
In 2020, DOD funded four PFAS treatment projects, for which TRS is a co-performer. The Environmental Security Technology Certification Program (ESTCP) funded two projects focused on thermal desorption of PFAS from soil using the FlexHeater® TCH technology. One of the 2021 field demonstration projects is focused on in situ PFAS removal from vadose zone soils; the other on ex situ removal from soil stockpiles.
How TCH allows TRS to treat more compounds
Because TCH can achieve far higher temperatures than ERH, TRS can treat semi-volatile compounds such as PFAS, PCBs, PAHs and dioxins in the vadose zone or above-grade in pile structures. Applying the FlexHeater® technology, TRS can provide more economical options for sites with minimal drilling access or deep treatment zones.
Additionally, TCH is effective in some materials where ERH is challenging, such as crystalline bedrock with little water, dry sediments, and highly saline environments. For example, the Arkansas site mentioned above has dry bedrock under the building, making ERH more difficult.
Further, TRS heaters are smaller and simpler than the heaters used in the past. Table 1 below compares various TCH approaches.
Table 1. Differences among TCH Heater Solutions
FlexHeater® Elements (patented and patent
pending)
Electrical resistive rod with nickel cold pin
Large copper coil using high frequency power
Gas burner at well- head
Cold section heat output
40-60 watts/foot or 15- 20% of heated section output
Modest (cables to the heater assembly)
High – gas must flow down and up
Boosting ratio at top and bottom
100% or higher, as needed (coil density can be varied)
25-40% (rods with modest diameter differences welded together)
Only via multiple heaters in each boring
No adjustment possible
Supplemental renewable energy for power
Yes – wind and solar Yes – wind and solar Yes – wind and solar No – burning fossil fuel
Energy source Electricity Electricity Electricity – requires frequency conversion
Natural gas or propane
Low (wire and ceramic disks)
Medium (solid rods and insulators)
Very high – complex assembly
High (gas burners on top of the heaters)
While gas energy may appear to be lower cost than electricity, it turns out that using electricity is generally the less expensive option, due to the actual useful power and energy delivered to the formation.
Figure 4. In Situ TCH of PFAS in Vadose Zone
Figure 5. Ex Situ TCH of PFAS
TRS Whitepaper on TCH March 2021 Page 5
We would be happy to discuss energy delivery options in detail with you. TRS continually strives to provide improved, less costly and robust TCH solutions.
References Oberle, D., G.L. Beyke, C. O'Brien, J. Seeman and E. Crownover. 2019. Flexible Helical Heater. U.S. Patent 10,201,042.
Stegemeier, G.L. and H.J. Vinegar. 2001. Thermal Conduction Heating for In Situ Desorption of Soils. Hazardous & Radioactive Waste Treatment Technologies Handbook. Boca Raton, FL: CRC Press.
About the Authors
Gorm Heron is Chief Technology Officer at TRS Group, Inc., [email protected]
Andrew Small is a Senior Project Manager at TRS Group, Inc. and Deputy General Manager at TRS China Tai Yan, [email protected]
TRS Group Taking Off with Thermal Conduction Heating
Gorm Heron, Andrew Small, Dan Oberle and Emily Crownover TRS Group, Inc.
Started in 2000, TRS Group (TRS) has been the premier provider of electrical resistance heating. To better serve our customers, TRS now provides three heating technologies:
• OptiFluxÒ Electrical Resistance Heating (ERH) – using electrodes, TRS passes electricity through the subsurface, achieving temperatures up to the boiling point of water.
• FlexHeaterÒ Thermal Conduction Heating (TCH) – TRS heats steel borings, transferring heat to the formation by conduction, reaching temperatures as high as 400oC among the borings.
• EcoSteamTM Steam Enhanced Extraction (SEE) – using injection and multiphase extraction wells, TRS injects steam into the formation and treats the collected fluids. Heating is limited to the temperature of steam.
Our research and development team has developed a patented TCH technology (Oberle et al. 2018) with targeted power delivery, reducing operating time and lowering costs.
TCH – what do you really need down-hole?
The steel casing reaches temperatures in the range of 300 to 800oC. When using electricity, it is important that the heater does not short to the casing. Therefore, the heater needs to be coated with a non-conductive material (silica, glass, ceramic) or centralized such that the metal part of the heater cannot touch the inside of the casing. As the heater wire is metal, TRS places ceramic spacers to prevent the wire from touching the casing, as shown in Figure 1. TRS offers multiple, patented and patent-pending FlexHeater® elements based on site conditions and goals. The TRS rod-style heater uses an alloy that is more flexible and sustainable than the systems others have used for decades. TRS uses this element in vertical, horizontal and angled boreholes, working around sensitive site infrastructure.
Heat movement is governed by matrix thermal diffusivity, which is the ratio of thermal conductivity to heat capacity. Thermal diffusivity varies with site stratigraphy and is based on water content, porosity and mineralogy. Even when these changes are modest (on the order of 1 to 3 times between a dry soil and wet clay), the ability of the formation to conduct heat away from the heater boring will vary.
The more uniform a site is heated, the less energy is used. A uniform heating profile requires different power inputs over depth. Therefore, it is desirable to control power delivery rates to different strata.
Some heaters accomplish this by varying the heater rod diameter, often with a boosted section at the top and bottom. TRS developed a heater with more flexibility in terms of power density over depth and time, allowing adjustment of the heat output as the collected data teaches us about the
Figure 1. FlexHeaterÒ element which provides flexibility to control power input
TRS Whitepaper on TCH March 2021 Page 2
formation. The TRS design allows us to remove, adjust and re-insert the heaters, enabling precise heating with less energy use.
Full-scale TCH remedy in North Carolina
TRS completed a FlexHeater® TCH full-scale project in North Carolina in 2019. The site had 32 heaters, each approximately 60 feet deep. Figure 2 shows a heater connection and the well field. Learning much about optimizing heater operations, TRS met the contractual goals and objectives.
Figure 2. FlexHeaterÒ TCH Operations in North Carolina in 2019
TCH Treatment in China
TRS China completed a large FlexHeater® TCH project in Nanjing, China. Operations with 420 heaters started in 2019. TRS China treated a 42,000 cubic meter source zone, concluding operations in 2020. The site was heavily contaminated with chlorophenols and other minimally volatile compounds. The value engineering designs for and lessons learned from this large, fast-paced project have been helpful for subsequent opportunities.
Figure 3. FlexHeaterÒ TCH Operations in Nanjing, China
TRS Whitepaper on TCH March 2021 Page 3
TCH at a Former Manufacturing Facility
TRS is implementing the FlexHeater® TCH technology under a large former manufacturing facility in Arkansas. TCH is well-suited to meet the challenging site conditions, which include limited access, dry vadose zone sediments, and interface to bedrock. TRS targeted three chlorinated volatile organic compounds (CVOCs) source zones with 154 vertical and angled heaters. TRS has removed over 4,000 pounds of CVOCs, achieved the remedial goals ahead of schedule in one of the areas and anticipates project completion by the Summer 2021.
Figure 3. An operating FlexHeaterÒ TCH site in Arkansas
Challenging TCH project under a large building in New Jersey
A commercial client approached TRS to apply TCH at a manufacturing facility in New Jersey. We are performing thermal treatment at depths of 50 to 120 feet below grade and installing more than four miles of heaters. Because much of the TCE source zone is located below the active facility, which must remain clean, TRS cannot drill from those rooms; instead, we are accessing the treatment zone from a separate room using angle drilling methods. To minimize costs, TRS designed, developed and tested a novel 200- foot long heater. We can install it at any angle and deliver depth-specific optimized power that allows for virtually no heating over the first 50 feet. The patent-pending design will keep the building cool, while heating the target zone to boiling temperatures. Installation started in 2020 and operations will start in 2021.
TCH treatment in Brazil
A TRS Doxor TCH project is in the design phase for implementation at a site in Sao Paulo, Brazil. The site is heavily contaminated by diesel range organics and has relatively stringent cleanup criteria for soil and groundwater. Using 113 FlexHeater® wells to deliver 500 kW or power to three source zones, TRS Doxor will complete the project in 2021.
Award of Two ESTCP Projects for PFAS Treatment using TCH
The remediation of per- and polyfluoroalkyl substances, also known as PFAS, is becoming increasingly important. The environmental industry is recognizing the challenges of developing analytical methods for
TRS Whitepaper on TCH March 2021 Page 4
PFAS in water, vapor and soil. At many U.S. Department of Defense (DOD) sites, stockpiles of untreated soil are growing, with no good or economical solution in sight. Source areas continue to leach PFAS to groundwater, impacting drinking water aquifers.
In 2020, DOD funded four PFAS treatment projects, for which TRS is a co-performer. The Environmental Security Technology Certification Program (ESTCP) funded two projects focused on thermal desorption of PFAS from soil using the FlexHeater® TCH technology. One of the 2021 field demonstration projects is focused on in situ PFAS removal from vadose zone soils; the other on ex situ removal from soil stockpiles.
How TCH allows TRS to treat more compounds
Because TCH can achieve far higher temperatures than ERH, TRS can treat semi-volatile compounds such as PFAS, PCBs, PAHs and dioxins in the vadose zone or above-grade in pile structures. Applying the FlexHeater® technology, TRS can provide more economical options for sites with minimal drilling access or deep treatment zones.
Additionally, TCH is effective in some materials where ERH is challenging, such as crystalline bedrock with little water, dry sediments, and highly saline environments. For example, the Arkansas site mentioned above has dry bedrock under the building, making ERH more difficult.
Further, TRS heaters are smaller and simpler than the heaters used in the past. Table 1 below compares various TCH approaches.
Table 1. Differences among TCH Heater Solutions
FlexHeater® Elements (patented and patent
pending)
Electrical resistive rod with nickel cold pin
Large copper coil using high frequency power
Gas burner at well- head
Cold section heat output
40-60 watts/foot or 15- 20% of heated section output
Modest (cables to the heater assembly)
High – gas must flow down and up
Boosting ratio at top and bottom
100% or higher, as needed (coil density can be varied)
25-40% (rods with modest diameter differences welded together)
Only via multiple heaters in each boring
No adjustment possible
Supplemental renewable energy for power
Yes – wind and solar Yes – wind and solar Yes – wind and solar No – burning fossil fuel
Energy source Electricity Electricity Electricity – requires frequency conversion
Natural gas or propane
Low (wire and ceramic disks)
Medium (solid rods and insulators)
Very high – complex assembly
High (gas burners on top of the heaters)
While gas energy may appear to be lower cost than electricity, it turns out that using electricity is generally the less expensive option, due to the actual useful power and energy delivered to the formation.
Figure 4. In Situ TCH of PFAS in Vadose Zone
Figure 5. Ex Situ TCH of PFAS
TRS Whitepaper on TCH March 2021 Page 5
We would be happy to discuss energy delivery options in detail with you. TRS continually strives to provide improved, less costly and robust TCH solutions.
References Oberle, D., G.L. Beyke, C. O'Brien, J. Seeman and E. Crownover. 2019. Flexible Helical Heater. U.S. Patent 10,201,042.
Stegemeier, G.L. and H.J. Vinegar. 2001. Thermal Conduction Heating for In Situ Desorption of Soils. Hazardous & Radioactive Waste Treatment Technologies Handbook. Boca Raton, FL: CRC Press.
About the Authors
Gorm Heron is Chief Technology Officer at TRS Group, Inc., [email protected]
Andrew Small is a Senior Project Manager at TRS Group, Inc. and Deputy General Manager at TRS China Tai Yan, [email protected]